This invention relates generally to track roller bearings with a sleeve or liner and more particularly to a sleeve member to which a self-lubricating bearing material is bonded.
Conventional track roller bearings are constructed of rolling elements positioned between inner and outer races, lubricated by grease. Periodic lubrication is required to maintain operational performance with added resistance to corrosion. The performance of these conventional track roller bearings also depends on the effectiveness of the bearing seals which not only ensures that the grease lubrication is maintained within the bearing but also that contamination from external sources is avoided.
Newer aircraft designs require that moving parts shall be able to operate for long periods of time with relatively little or no maintenance. For example, bearings provided for the operation of ailerons on aircraft should be able to operate through tens of thousands of revolutions without any maintenance. Conventional roller bearings may have to be greased after 5,000 revolutions.
In one approach to this periodic maintenance requirement, a bearing liner is attached to the bearing surface of the outer race. The bearing liner contains a self-lubricating bearing material such as polytetrafluorethylene. As an alternative, the self-lubricating bearing material has been attached to the bearing surface of the inner race.
Neither alternative using an attached bearing liner has been satisfactory. The bearing liner attached to the outer race frequently fails to achieve desired lifetimes due to fatigue failure. The liner is subject to a ploughing action by induced liner deflection when loaded by the inner race during rotation of the outer race. Self-lubricating bearing liners attached to the bearing surface of the inner race are subject to premature wear. In typical aircraft applications, the inner race is fixed and does not rotate. The outer race bearing surface will bear against a limited portion of the inner race bearing liner, that portion which is in line with the applied load. In this instance, all the wear is to a small portion of the bearing liner which will prematurely wear out.
Another alternative adds a sleeve of self-lubricating bearing material between the inner race and the outer race. The sleeve is free to float between the races. The bearing sleeve periodically and randomly sticks to one bearing surface or the other. This random sticking can cause uneven wear and premature failure of the bearing.
The foregoing illustrates limitations known to exist in present track roller bearings. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.